GENERATION AND PROFILING OF FULLY HUMAN HuCAL GOLD-DERIVED THERAPEUTIC ANTIBODIES SPECIFIC FOR HUMAN CD38

ABSTRACT

The present invention provides novel antibodies and methods for using recombinant antigen-binding regions and antibodies and functional fragments containing such antigen-binding regions that are specific for CD38, which plays an integral role in various disorders or conditions. These methods take advantage of newly discovered antibodies and surprising properties of such antibodies, such as the ability to bind CD38 of minipig origin and the ability to induce, by cross-linking, specific killing of cells that express CD38. These antibodies as well as the novel methods for using those antibodies can be used to treat, for example, hematological malignancies such as multiple myeloma.

This patent application is a continuation of U.S. patent application Ser. No. 16/125,307 filed Sep. 7, 2018, which is continuation of U.S. application Ser. No. 14/877,958 filed Oct. 8, 2015, issued as U.S. Pat. No. 10,184,005 on Jan. 22, 2019, which is a divisional of U.S. application Ser. No. 13/918,199 filed Jun. 14, 2013, issued as U.S. Pat. No. 9,193,799 on Nov. 24, 2015, which is a divisional of U.S. application Ser. No. 13/291,473 filed Nov. 8, 2011 which issued as U.S. Pat. No. 8,486,394 on Jul. 16, 2013, which is a divisional of U.S. application Ser. No. 12/089,806 filed Apr. 10, 2008 which issued as U.S. Pat. No. 8,088,896 on Jan. 3, 2012 which is the U.S. National Stage Application of PCT/EP2006/009889 filed Oct. 12, 2006 and which claims priority to U.S. Provisional Application Ser. No. 60/725,297 filed Oct. 12, 2005, teachings of each of which are incorporated herein by reference in their entireties.

SUMMARY OF THE INVENTION

The present invention relates to an isolated antigen-binding region that is specific for CD38, which comprises (i) an H-CDR3 region depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106 or (ii) an H-CDR3 region that has at least a sixty percent identity to an H-CDR3 region depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106

The present invention furthermore relates to an isolated antibody or functional fragment thereof that is specific for CD38, which comprises (i) a variable heavy chain depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106 or (ii) a variable heavy chain that has at least a sixty percent identity to a variable heavy chain depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106.

Additionally, the present invention relates to an isolated antigen-binding region that is specific for CD38, which comprises (i) an L-CDR3 region depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110 or (ii) an L-CDR3 region that has at least a sixty percent identity to an L-CDR3 region depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110.

Also, the present invention relates to an isolated antibody or functional fragment thereof, which comprises (i) a variable light chain depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110 or (ii) a variable light chain that has at least a sixty percent identity to a variable light chain depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110.

The present invention further relates to a variable heavy chain of an isolated antigen-binding region that is encoded by (i) a nucleic acid sequence comprising SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or 91 or (ii) a nucleic acid sequences that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or 91, wherein said antigen-binding region is specific for CD38.

The present invention also relates to a variable light chain of an isolated antigen-binding region that is encoded by (i) a nucleic acid sequence comprising SEQ ID NO: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 or 108 or (ii) a nucleic acid sequences that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 or 108, wherein said antibody or functional fragment thereof is specific for CD38.

Further, the present invention relates to an isolated nucleic acid sequence that encodes an antigen-binding region of a human antibody or functional fragment thereof that is specific for CD38.

Additionally, the invention relates to a nucleic acid sequence encoding a variable heavy chain of an isolated antigen-binding region, which comprises (i) a sequence selected from the group consisting of SEQ ID NOS: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 and 91 or (ii) a nucleic acid sequence that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or 91, wherein said antigen-binding region is specific for CD38.

The present invention also relates to a nucleic acid sequence encoding a variable light chain of an isolated antigen-binding region, which comprises (i) a sequence selected from the group consisting of SEQ ID NOS: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 and 108 or (ii) a nucleic acid sequence that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 or 108 wherein said antigen-binding region is specific for CD38.

The present invention further relates to a method of inducing specific killing of tumor cells that express CD38, wherein said specific killing occurs by CD38 cross-linking, comprising the step of incubating said cells in the presence of a sufficient amount of an isolated human or humanized anti-CD38 antibody or a functional fragment thereof, wherein said human or humanized anti-CD38 antibody comprises (i) a nucleic acid sequence encoding a heavy chain depicted in SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or 91 or (ii) a nucleic acid sequences that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or 91, wherein said antibody or a functional fragment thereof is specific for CD38.

Additionally, the present invention relates to A method of inducing specific killing of tumor cells that express CD38, wherein said specific killing occurs by CD38 cross-linking, comprising the step of incubating said cells in the presence of a sufficient amount of an isolated human or humanized anti-CD38 antibody or a functional fragment thereof, wherein said human or humanized anti-CD38 antibody comprises (i) a nucleic acid sequence encoding a light chain depicted in SEQ ID NO: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 or 108 or (ii) a nucleic acid sequences that hybridizes under high stringency conditions to the complementary strand of SEQ ID NO: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 107 or 108, wherein said antibody or a functional fragment thereof is specific for CD38.

Also, the present invention relates to a method of inducing specific killing of tumor cells that express CD38, wherein said specific killing occurs by CD38 cross-linking, comprising the step of incubating said cells in the presence of a sufficient amount of an isolated human or humanized anti-CD38 antibody or a functional fragment thereof, wherein said human or humanized anti-CD38 antibody or said functional fragment thereof comprises (i) a heavy chain amino acid sequence depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106 or (ii) a variable heavy chain that has at least a sixty percent identity to a variable heavy chain depicted in SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 or 106.

Also, the present invention relates to a method of inducing specific killing of tumor cells that express CD38, wherein said specific killing occurs by CD38 cross-linking, comprising the step of incubating said cells in the presence of a sufficient amount of an isolated human or humanized anti-CD38 antibody or a functional fragment thereof, wherein said human or humanized anti-CD38 antibody comprises (i) and/or a light chain amino acid sequence depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110 or (ii) a variable light chain that has at least a sixty percent identity to a variable light chain depicted in SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 or 110.

Furthermore, the present invention relates to a method of detecting specific killing of tumor cells that express CD38, by CD38 cross-linking, comprising the steps of:

-   -   (i) administering to a subject in need thereof an effective         amount of a human or humanized anti-CD38 antibody or a         functional fragment thereof, and     -   (ii) detecting the specific killing activity of said human or         humanized anti-CD38 antibody or said functional fragment         thereof.

Also, the present invention relates to a method of detecting the presence of CD38 in a tissue or a cell of minipig origin, comprising the steps of:

-   -   (i) allowing a human or humanized anti-CD38 antibody or a         functional fragment thereof to come into contact with said CD38,         and     -   (ii) detecting the specific binding of said human or humanized         anti-CD38 antibody or functional fragment thereof to said CD38         minipig cells, wherein said antibody or functional fragment         thereof is also able to specifically bind to CD38 of human         origin.

Furthermore, the present invention relates to A method of detecting CD38 in a CD38-expressing erythrocyte, comprising the steps of:

-   -   (i) allowing a human or humanized anti-CD38 antibody or a         functional fragment thereof to come into contact with said         CD38-expressing erythrocyte, and     -   (ii) detecting the specific binding of said human or humanized         anti-CD38 antibody or functional fragment thereof to said         CD38-expressing erythrocytes, wherein said antibody or         functional fragment thereof is also able to specifically bind to         human CD38 from a cell or tissue other than human erythrocytes.

The present invention also relates to an isolated antibody or functional fragment thereof according to the present invention, which comprises (i) an H-CDR3 region depicted in SEQ ID NO: 21 or 22 or (ii) an H-CDR3 region at least a sixty percent identity thereto, and that is specific for human CD38 and marmoset CD38.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1a provides nucleic acid sequences of various antibody variable heavy regions for use in the present invention.

FIG. 1b provides amino acid sequences of various antibody variable heavy regions for use in the present invention. CDR regions HCDR1, HCDR2 and HCDR3 are designated from N- to C-terminus in boldface.

FIG. 2a provides nucleic acid sequences of various antibody variable light regions for use in the present invention.

FIG. 2b provides amino acid sequences of various antibody variable light regions for use in the present invention. CDR regions LCDR1, LCDR2 and LCDR3 are designated from N- to C-terminus in boldface.

FIG. 3 provides amino acid sequences of variable heavy regions of various consensus-based HuCAL antibody master gene sequences. CDR regions HCDR1, HCDR2 and HCDR3 are designated from N- to C-terminus in boldface.

FIG. 4 provides amino acid sequences of variable light regions of various consensus-based HuCAL antibody master gene sequences. CDR regions LCDR1, LCDR2 and LCDR3 are designated from N- to C-terminus in boldface.

FIG. 5 provides the amino acid sequence of CD38 (SWISS-PROT primary accession number P28907).

FIG. 6 provides the nucleotide sequences of the heavy and light chains of chimeric OKT10.

FIG. 7 provides the DNA sequence of pMORPH®_h_IgG1_1 (bp 601-2100) (SEQ ID NO: 74): The vector is based on the pcDNA3.1+ vectors (Invitrogen). The amino acid sequence of the VH-stuffer sequence is indicated in bold, whereas the final reading frames of the VH-leader sequence and the constant region gene are printed in non-bold. Restriction sites are indicated above the sequence. The priming sites of the sequencing primers are underlined.

FIG. 8 provides the DNA sequence of Ig kappa light chain expression vector pMORPH®_h_Igκ_1 (bp 601-1400) (SEQ ID NO: 75): The vector is based on the pcDNA3.1+ vectors (Invitrogen). The amino acid sequences of the Vκ-stuffer sequence is indicated in bold, whereas the final reading frames of the Vκ-leader sequence and of the constant region gene are printed in non-bold. Restriction sites are indicated above the sequence. The priming sites of the sequencing primers are underlined.

FIG. 9 provides the DNA sequence of HuCAL Ig lambda light chain vector pMORPH®_h_Igλ_1 (bp 601-1400) (SEQ ID NO: 76): The amino acid sequence of the Vλ-stuffer sequence is indicated in bold, whereas the final reading frames of the VW-leader sequence and of the constant region gene are printed in non-bold. Restriction sites are indicated above the sequence. The priming sites of the sequencing primers are underlined.

FIG. 10 provides different combinations of heavy and light chains in the Fab/IgG format for use in the present invention

FIG. 11 provides CD38-expression analysis of Lymphocytes and Erythrocytes obtained by FACS. PBMCs and Erythrocytes were isolated from whole blood of cynomolgus, rhesus and marmoset by density gradient centrifugation followed by FACS-analysis using anti-CD38 Fab antibodies MOR03087 (A, right histograms, light arrow) and MOR03088 (B, right histograms; light arrow). An irrelevant Fab-antibody (A & B, left histograms; black arrow) was used as a negative control.

FIG. 12 provides CD38 expression analysis of Lymphocytes and Erythrocytes obtained by FACS. PBMCs and Erythrocytes were isolated from whole blood of human, cynomolgus and marmoset by density gradient centrifugation followed by FACS-analysis using anti-CD38 IgG1 MOR03087 (right histograms; white arrow). An irrelevant IgG1 control antibody (A & B, left histograms; black arrow) was used as a negative control.

FIG. 13 provides a comparative overview of Cross-Reactivity of different anti-CD38 antibodies.

FIGS. 14(a) and 14(b) delineate the CDR and FR regions for certain antibodies for use in the invention and compare amino acids at a given position to each other and to corresponding consensus sequences.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is based on the discovery of novel antibodies and methods of using antibodies that are specific to or have a high affinity for CD38 and can deliver a therapeutic benefit to a subject. The antibodies, which may be human or humanized, can be used in many contexts, which are more fully described herein. Suitable antibodies for use in the present invention are disclosed in U.S. 60/614,471, which hereby is incorporated by reference.

A “human” antibody or functional human antibody fragment is hereby defined as one that is not chimeric (e.g., not “humanized”) and not from (either in whole or in part) a non-human species. A human antibody or functional antibody fragment can be derived from a human or can be a synthetic human antibody. A “synthetic human antibody” is defined herein as an antibody having a sequence derived, in whole or in part, in silico from synthetic sequences that are based on the analysis of known human antibody sequences. In silico design of a human antibody sequence or fragment thereof can be achieved, for example, by analyzing a database of human antibody or antibody fragment sequences and devising a polypeptide sequence utilizing the data obtained therefrom. Another example of a human antibody or functional antibody fragment, is one that is encoded by a nucleic acid isolated from a library of antibody sequences of human origin (i.e., such library being based on antibodies taken from a human natural source).

A “humanized antibody” or functional humanized antibody fragment is defined herein as one that is (i) derived from a non-human source (e.g., a transgenic mouse which bears a heterologous immune system), which antibody is based on a human germline sequence; or (ii) chimeric, wherein the variable domain is derived from a non-human origin and the constant domain is derived from a human origin or (iii) CDR-grafted, wherein the CDRs of the variable domain are from a non-human origin, while one or more frameworks of the variable domain are of human origin and the constant domain (if any) is of human origin.

As used herein, an antibody “binds specifically to,” is “specific to/for” or “specifically recognizes” an antigen (here, CD38) if such antibody is able to discriminate between such antigen and one or more reference antigen(s), since binding specificity is not an absolute, but a relative property. In its most general form (and when no defined reference is mentioned), “specific binding” is referring to the ability of the antibody to discriminate between the antigen of interest and an unrelated antigen, as determined, for example, in accordance with one of the following methods. Such methods comprise, but are not limited to Western blots, ELISA-, RIA-, ECL-, IRMA-tests, FACS, IHC and peptide scans. For example, a standard ELISA assay can be carried out. The scoring may be carried out by standard color development (e.g. secondary antibody with horseradish peroxide and tetramethyl benzidine with hydrogenperoxide). The reaction in certain wells is scored by the optical density, for example, at 450 nm. Typical background (=negative reaction) may be 0.1 OD; typical positive reaction may be 1 OD. This means the difference positive/negative can be more than 10-fold. Typically, determination of binding specificity is performed by using not a single reference antigen, but a set of about three to five unrelated antigens, such as milk powder, BSA, transferrin or the like. It is possible for an antibody to be “specific to” or “specific for” an antigen of 2 or more cells/tissues and/or 2 or more species, provided that the antibody meets binding criteria for each of such cells/tissues and species, for example. Accordingly, an antibody may bind specifically to the target antigen CD38 on various cell types and/or tissues, e.g. erythrocytes, lymphocytes isolated from peripheral blood, spleen or lymph-nodes. In addition, an antibody may be specific to both CD38 of one species and CD38 of another species.

“Specific binding” also may refer to the ability of an antibody to discriminate between the target antigen and one or more closely related antigen(s), which are used as reference points, e.g. between CD38 and CD157. Additionally, “specific binding” may relate to the ability of an antibody to discriminate between different parts of its target antigen, e.g. different domains or regions of CD38, such as epitopes in the N-terminal or in the C-terminal region of CD38, or between one or more key amino acid residues or stretches of amino acid residues of CD38.

Also, as used herein, an “immunoglobulin” (Ig) hereby is defined as a protein belonging to the class IgG, IgM, IgE, IgA, or IgD (or any subclass thereof), and includes all conventionally known antibodies and functional fragments thereof. A “functional fragment” of an antibody/immunoglobulin hereby is defined as a fragment of an antibody/immunoglobulin (e.g., a variable region of an IgG) that retains the antigen-binding region. An “antigen-binding region” of an antibody typically is found in one or more hypervariable region(s) of an antibody, i.e., the CDR-1, -2, and/or -3 regions; however, the variable “framework” regions can also play an important role in antigen binding, such as by providing a scaffold for the CDRs. Preferably, the “antigen-binding region” comprises at least amino acid residues 4 to 103 of the variable light (VL) chain and 5 to 109 of the variable heavy (VH) chain, more preferably amino acid residues 3 to 107 of VL and 4 to 111 of VH, and particularly preferred are the complete VL and VH chains (amino acid positions 1 to 109 of VL and 1 to 113 of VH; numbering according to WO 97/08320). A preferred class of immunoglobulins for use in the present invention is IgG. “Functional fragments” of the invention include the domain of a F(ab′)₂ fragment, a Fab fragment and scFv. The F(ab′)₂ or Fab may be engineered to minimize or completely remove the intermolecular disulphide interactions that occur between the C_(H1) and C_(L) domains.

The term “parental binder” as used in connection with the present invention denotes any binder which has not undergone the process of optimization. A process of optimization is described elsewhere in the present specification.

The term “binder” as used in connection with the present invention may be used in a synonymous manner as the term “immunoglobulin” or “antibody”.

An antibody for use in the invention may be derived from a recombinant antibody library that is based on amino acid sequences that have been designed in silico and encoded by nucleic acids that are synthetically created. In silico design of an antibody sequence is achieved, for example, by analyzing a database of human sequences and devising a polypeptide sequence utilizing the data obtained therefrom. Methods for designing and obtaining in silico-created sequences are described, for example, in Knappik et al., J. Mol. Biol. (2000) 296:57; Krebs et al., J. Immunol. Methods. (2001) 254:67; and U.S. Pat. No. 6,300,064 issued to Knappik et al., which hereby are incorporated by reference in their entirety.

Antibodies for Use in the Invention

Throughout this document, reference is made to the following representative antibodies for use in the invention: “antibody nos.” or “LACS” or “MOR” 3076 or 03076, 3078 or 03078, 3081 or 03081, 3085 or 03085, 3086 or 03086, 3087 or 03087, 3088 or 03088, 3089 or 03089, 3101 or 03101, 3102 or 03102, 3127 or 03127, 3128 or 03128, 3129 or 03129, 3130 or 03130, 3131 or 03131, 6183 or 06183, 6184 or 06184, 6185 or 06185, 6186 or 06186, 6187 or 06187, 6188 or 06188, 6189 or 06189, 6190 or 06190, 6192 or 06192, 6195 or 06195, 6197 or 06197, 6200 or 06200, 6201 or 06201, 6204 or 06204, 6214 or 06214, 6278 or 06278, 6279 or 06279. LAC 3076 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 1 (DNA)/SEQ ID NO: 16 (protein) and a variable light region corresponding to SEQ ID NO: 31 (DNA)/SEQ ID NO: 46 (protein). LAC 3078 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 2 (DNA)/SEQ ID NO: 17 (protein) and a variable light region corresponding to SEQ ID NO: 32 (DNA)/SEQ ID NO: 47 (protein). LAC 3081 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 3 (DNA)/SEQ ID NO: 18 (protein) and a variable light region corresponding to SEQ ID NO: 33 (DNA)/SEQ ID NO: 48 (protein). LAC 3085 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 4 (DNA)/SEQ ID NO: 19 (protein) and a variable light region corresponding to SEQ ID NO: 34 (DNA)/SEQ ID NO: 49 (protein). LAC 3086 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 5 (DNA)/SEQ ID NO: 20 (protein) and a variable light region corresponding to SEQ ID NO: 35 (DNA)/SEQ ID NO: 50 (protein). LAC 3087 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 6 (DNA)/SEQ ID NO: 21 (protein) and a variable light region corresponding to SEQ ID NO: 36 (DNA)/SEQ ID NO: 51 (protein). LAC 3088 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 7 (DNA)/SEQ ID NO: 22 (protein) and a variable light region corresponding to SEQ ID NO: 37 (DNA)/SEQ ID NO: 52 (protein). LAC 3089 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 8 (DNA)/SEQ ID NO: 23 (protein) and a variable light region corresponding to SEQ ID NO: 38 (DNA)/SEQ ID NO: 53 (protein). LAC 3101 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 9 (DNA)/SEQ ID NO: 24 (protein) and a variable light region corresponding to SEQ ID NO: 39 (DNA)/SEQ ID NO: 54 (protein). LAC 3102 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 10 (DNA)/SEQ ID NO: 25 (protein) and a variable light region corresponding to SEQ ID NO: 40 (DNA)/SEQ ID NO: 55 (protein). LAC 3127 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 11 (DNA)/SEQ ID NO: 26 (protein) and a variable light region corresponding to SEQ ID NO: 41 (DNA)/SEQ ID NO: 56 (protein). LAC 3128 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 12 (DNA)/SEQ ID NO: 27 (protein) and a variable light region corresponding to SEQ ID NO: 42 (DNA)/SEQ ID NO: 57 (protein). LAC 3129 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 13 (DNA)/SEQ ID NO: 28 (protein) and a variable light region corresponding to SEQ ID NO: 43 (DNA)/SEQ ID NO: 58 (protein). LAC 3130 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 14 (DNA)/SEQ ID NO: 29 (protein) and a variable light region corresponding to SEQ ID NO: 44 (DNA)/SEQ ID NO: 59 (protein). LAC 3131 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 15 (DNA)/SEQ ID NO: 30 (protein) and a variable light region corresponding to SEQ ID NO: 45 (DNA)/SEQ ID NO: 60 (protein). Furthermore, optimized clones, which were derived from the parental binders MOR03087 and MOR03088, comprise the following: MOR06183 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 77 (DNA)/SEQ ID NO: 92 (protein). MOR06184 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 78 (DNA)/SEQ ID NO: 93 (protein). MOR06185 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 79 (DNA)/SEQ ID NO: 94 (protein). MOR06186 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 80 (DNA)/SEQ ID NO: 95 (protein). MOR06187 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 81 (DNA)/SEQ ID NO: 96 (protein). MOR06188 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 82 (DNA)/SEQ ID NO: 97. MOR06189 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 83 (DNA)/SEQ ID NO:98 (protein). MOR06190 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 84 (DNA)/SEQ ID NO: 99 (protein). MOR06192 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 85 (DNA)/SEQ ID NO: 100 (protein). MOR06195 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 86 (DNA)/SEQ ID NO: 101 (protein). MOR06197 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 87 (DNA)/SEQ ID NO: 102 (protein). MOR06200 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 88 (DNA)/SEQ ID NO: 103 (protein). MOR06201 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 89 (DNA)/SEQ ID NO: 104 (protein). MOR 06204 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 90 (DNA)/SEQ ID NO: 105 (protein). MOR06214 represents an antibody having a variable heavy region corresponding to SEQ ID NO: 91 (DNA)/SEQ ID NO: 106 (protein). MOR06278 represents an antibody having a variable light region corresponding to SEQ ID NO: 107 (DNA)/SEQ ID NO: 109 (protein). MOR 06279 represents an antibody having a variable light region corresponding to SEQ ID NO: 108 (DNA)/SEQ ID NO: 110 (protein).

Antibodies of the invention were characterized in Fab and/or IgG format and comprise various combinations of the light and heavy chains of optimized and parental binders. FIG. 10 shows several non-limiting combinations which can be used in connection with the present invention.

In one aspect, the invention provides methods for using antibodies having an antigen-binding region that can bind specifically to or has a high affinity for one or more regions of CD38, whose amino acid sequence is depicted by SEQ ID NO: 71. An antibody is said to have a “high affinity” for an antigen if the affinity measurement is at least 100 nM (monovalent affinity of Fab fragment). An antibody or antigen-binding region for use in the present invention preferably can bind to CD38 with an affinity of about less than 600 nM. Preferably, the antibody or antigen-binding region for use in the present invention can bind to CD38 with an affinity of about less than 100 nM, more preferably less than about 60 nM, and still more preferably less than about 30 nM. Further preferred are uses of antibodies that bind to CD38 with an affinity of less than about 10 nM, and more preferably less than 3 about nM. For instance, the affinity of an antibody for use in the invention against CD38 may be about 10.0 nM or 2.4 nM (monovalent affinity of Fab fragment).

Table 1 provides a summary of affinities of representative antibodies, as determined by surface plasmon resonance (Biacore) and FACS Scatchard analysis:

TABLE 1 Antibody Affinities BIACORE (Fab) FACS Scatchard (IgG1)^(b) Antibody (Fab or IgG1) K_(D) [nM]^(a) K_(D) [nM] MOR03076 440/596 n.d. MOR03078 n.d. n.d. MOR03081 416/450   2.5 MOR03085 122 10  MOR03086  30 n.d. MOR03087 17/38 5 MOR03088  95 n.d. MOR03089 340 n.d. MOR03101 314 n.d. MOR03102  64 5 MOR03127 168 (54)^(c) n.d. MOR03128 117/84^(d) n.d. MOR03129  43 n.d. MOR03130 n.d. n.d. MOR03131 451 n.d. Chimeric OKT10 n.d.   8.28 ^(a)Fab format; analysis on human CD38 Fc-fusion aa 45-300 ^(b)IgG1 format; analysis with Raji cells ^(c)standard deviation (n = 3) ^(d)standard deviation (n = 4)

With reference to Table 1, the affinity of LACs was measured by surface plasmon resonance (Biacore) on human CD38 Fc-fusion and by a flow cytometry procedure utilizing the CD38-expressing human Raji cell line. The Biacore studies were performed on directly immobilized antigen (CD38-Fc fusion protein). The Fab format of LACs exhibit an monovalent affinity range between about 30 and 596 nM on immobilized CD38-Fe fusion protein.

The IgG1 format was used for the cell-based affinity determination (FACS Scatchard). The right column of Table 1 denotes the binding strength of the LACS in this format.

Another preferred feature of preferred antibodies for use in the invention is their specificity for an area within the N-terminal region of CD38. For example, LACs of the invention can bind specifically to the N-terminal region of CD38.

Optimized antibodies of the present invention were further characterized as shown in Tables 2 and 3. Summaries are provided of affinities as determined by surface plasmon resonance (Biacore) and FACS Scatchard analysis. Additionally, FACS-binding to human erythrocytes and ELISA binding studies to CD38 Fc-Fusion protein have also been determined. The characterizations show that several optimized binders show a reduced binding to human erythrocytes and a higher ELISA signal as compared to the parental clone. In addition derivatives of MOR03088 have an improved affinity as shown by FACS Scatchards and affinity determinations.

TABLE 2 Overview characterizations of affinity-matured clones: FACS anal. FACS-Binding ELISA Affinities to human CD38 Fc-Fusion KDs KDs Scatchards [EC₅₀s] Erythrocytes^(b) protein^(b) (Biacore)^(a) (Bioveris)^(a) RPMI8226^(a) OPM2^(b) (Compared to Efficacy (% Reactivity of MOR# Optimization [nM] [pM] [nM] [nM] MOR030871 ADCC^(b,c) MOR03087) 03087 Parental 5.68 48.77 5.37 17.4*/5.7 =MOR03087 + 100 6183 H-CDR2 13.47 25.98 28.06 8.91 <MOR03087 + 106 6184 H-CDR2 9.68 66.22 4.01 10.58 ~MOR03087 n.d. 150 6185 H-CDR2 4.39 13.69 7.30 11.50 <MOR03087 + 142 6186 H-CDR2 4.62 5.09 6.47 15.57 <MOR03087 n.d. 117 6187 H-CDR2 12.46 45.38 16.85 9.37 ~MOR03087 n.d. 145 6188 H-CDR2 3.96 59.32 22.71 20.15 <MOR03087 n.d. 140 6189 H-CDR2 4.95 24.69 9.41 n.e. ~MOR03087 n.d. 126 6190 H-CDR2 15.65 48.85 11.66 n.e. <MOR03087 n.d. 125 6192 H-CDR2 5.01 74.73 7.07 n.e. ~MOR03087 n.d. 111 6195 H-CDR2 4.52 55.73 5.60 n.e. ~MOR03087 n.d. 155 6197 H-CDR2 4.81 12.74 6.92 n.e. <MOR03087 n.d. 138 6200 H-CDR2 7.92 59.91 5.02 7.15 >MOR03087 n.d. 144 6201 H-CDR2 6.81 18.59 9.00 n.e. ~MOR03087 n.d. 137 03088 Parental 41.40 2149.92 24.6* 15.3* no binding + 18 6204 H-CDR2 22.72 58.51 6.36 n.e. <MOR03087 n.d. 56 6214 H-CDR2 5.26 93.65 5.32 n.e. <MOR03087 n.d. 109 6347 L-CDR3 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 6348 L-CDR3 n.d. n.d. n.d. n.d. n.d. n.d. n.d. ^(a)Fab-format ^(b)IgG-format ^(c)Human Effector cells & RPMI8226 Target cells (E:T ratio = 30:1) +: Killing of RPMI8226 cells in ADCC n.d.: not determined *different experiment

TABLE 3 EC₅₀ in FACS-Scatchard, ADCC and CDC Characterizations FACS-Scatchard ADCC CDC RPMI8226 CCRF-CEM OPM2 RPMI8226 CHO Anti-CD38 MAbs: EC₅₀ [nM]^(a) EC₅₀ [nM]^(a) EC₅₀ [nM]^(b) EC₅₀ [nM]^(b) EC₅₀ [nM]^(a) MOR03087 6.3 14.7 17.54 0.14 3.4 MOR03088 24.6 25.5 2.6 n.e. n.e. MOR03080 1.8 2.6 1.9 0.13 1.9 ^(a)single measurement ^(b)mean from 2 measurements

The type of epitope to which an antibody for use in the invention binds may be linear (i.e. one consecutive stretch of amino acids) or conformational (i.e. multiple stretches of amino acids). In order to determine whether the epitope of a particular antibody is linear or conformational, the skilled worker can analyze the binding of antibodies to overlapping peptides (e.g., 13-mer peptides with an overlap of 11 amino acids) covering different domains of CD38. LACS may recognize discontinuous or linear epitopes in the N-terminal region of CD38. Combined with the knowledge provided herein, the skilled worker in the art will know how to use one or more isolated epitopes of CD38 for generating antibodies having an antigen-binding region that is specific for said epitopes (e.g. using synthetic peptides of epitopes of CD38 or cells expressing epitopes of CD38).

An antibody for use in the invention preferably is species cross-reactive with humans and at least one other non-human species. The non-human species can be non-human primate, e.g. rhesus, baboon and/or cynomolgus. Other non-human species can be minipig, rabbit, mouse, rat and/or hamster. An antibody that is cross reactive with at least one other species beside human can provide greater flexibility and benefits over known anti-CD38 antibodies, for purposes of conducting in vivo studies in multiple species with the same antibody. An antibody that is cross reactive with minipig and/or rabbit, for example, can be a candidate for toxicology and safety studies.

Preferably, an antibody for use in the invention not only is able to bind to CD38, but also is able to mediate killing of a cell expressing CD38. More specifically, an antibody for use in the invention can mediate its therapeutic effect by depleting CD38-positive (e.g., malignant) cells via antibody-effector functions. These functions include antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).

CD38-expression, however, is not only found on immune cells within the myeloid (e.g. monocytes, granulocytes) and lymphoid lineage (e.g. activated B and T-cells; plasma cells), but also on the respective precursor cells. Since it is important that those cells are not affected by antibody-mediated killing of malignant cells, the antibodies of the present invention are preferably not cytotoxic to precursor cells.

In addition to its catalytic activities as a cyclic ADP-ribose cyclase and hydrolase, CD38 displays the ability to transduce signals of biological relevance (Hoshino et al., 1997; Ausiello et al., 2000). Those functions can be induced in vivo by, e.g. receptor-ligand interactions or by cross-linking with agonistic anti-CD38 antibodies, leading, e.g. to calcium mobilization, lymphocyte proliferation and release of cytokines. Preferably, the antibodies of the present invention are non-agonistic antibodies.

Peptide Variants

Antibodies for use in the invention are not limited to the specific peptide sequences provided herein. Rather, the invention also embodies the use of variants of these polypeptides. With reference to the instant disclosure and conventionally available technologies and references, the skilled worker will be able to prepare, test and utilize functional variants of the antibodies disclosed herein, while appreciating that variants having the ability to mediate killing of a CD38+ target cell fall within the scope of the present invention. As used in this context, “ability to mediate killing of a CD38+ target cell” means a functional characteristic ascribed to an anti-CD38 antibody for use in the invention. Ability to mediate killing of a CD38+ target cell, thus, includes the ability to mediate killing of a CD38+ target cell, e.g. by ADCC and/or CDC, or by toxin constructs conjugated to an antibody for use in the invention.

A variant can include, for example, an antibody that has at least one altered complementarity determining region (CDR) (hyper-variable) and/or framework (FR) (variable) domain/position, vis-à-vis a peptide sequence disclosed herein. To better illustrate this concept, a brief description of antibody structure follows.

An antibody is composed of two peptide chains, each containing one (light chain) or three (heavy chain) constant domains and a variable region (VL, VH), the latter of which is in each case made up of four FR regions and three interspaced CDRs. The antigen-binding site is formed by one or more CDRs, yet the FR regions provide the structural framework for the CDRs and, hence, play an important role in antigen binding. By altering one or more amino acid residues in a CDR or FR region, the skilled worker routinely can generate mutated or diversified antibody sequences, which can be screened against the antigen, for new or improved properties, for example.

FIGS. 14 a (VH) and 14 b (VL) delineate the CDR and FR regions for certain antibodies for use in the invention and compare amino acids at a given position to each other and to corresponding consensus or “master gene” sequences (as described in U.S. Pat. No. 6,300,064).

The skilled worker will be able to design peptide variants, the use of which is within the scope of the present invention. It is preferred that variants are constructed by changing amino acids within one or more CDR regions; a variant might also have one or more altered framework regions. Alterations also may be made in the framework regions. For example, a peptide FR domain might be altered where there is a deviation in a residue compared to a germline sequence.

Furthermore, variants may be obtained by using one LAC as starting point for optimization by diversifying one or more amino acid residues in the LAC, preferably amino acid residues in one or more CDRs, and by screening the resulting collection of antibody variants for variants with improved properties. Particularly preferred is diversification of one or more amino acid residues in CDR-3 of VL, CDR-3 of VH, CDR-1 of VL and/or CDR-2 of VH. Diversification can be done by synthesizing a collection of DNA molecules using trinucleotide mutagenesis (TRIM) technology (Vimekäs, B., Ge, L., Plückthun, A., Schneider, K. C., Wellnhofer, G., and Moroney S. E. (1994) Trinucleotide phosphoramidites: ideal reagents for the synthesis of mixed oligonucleotides for random mutagenesis. Nucl. Acids Res. 22, 5600).

Conservative Amino Acid Variants

Polypeptide variants may be made that conserve the overall molecular structure of an antibody peptide sequence described herein. Given the properties of the individual amino acids, some rational substitutions will be recognized by the skilled worker. Amino acid substitutions, i.e., “conservative substitutions,” may be made, for instance, on the basis of similarity in polarity, charge, solubility, hydrophobicity, hydrophilicity, and/or the amphipathic nature of the residues involved.

For example, (a) nonpolar (hydrophobic) amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan, and methionine; (b) polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, and glutamine; (c) positively charged (basic) amino acids include arginine, lysine, and histidine; and (d) negatively charged (acidic) amino acids include aspartic acid and glutamic acid. Substitutions typically may be made within groups (a)-(d). In addition, glycine and proline may be substituted for one another based on their ability to disrupt α-helices. Similarly, certain amino acids, such as alanine, cysteine, leucine, methionine, glutamic acid, glutamine, histidine and lysine are more commonly found in α-helices, while valine, isoleucine, phenylalanine, tyrosine, tryptophan and threonine are more commonly found in β-pleated sheets. Glycine, serine, aspartic acid, asparagine, and proline are commonly found in turns. Some preferred substitutions may be made among the following groups: (i) S and T; (ii) P and G; and (iii) A, V, L and I. Given the known genetic code, and recombinant and synthetic DNA techniques, the skilled scientist readily can construct DNAs encoding the conservative amino acid variants. In one particular example, amino acid position 3 in SEQ ID NOS: 5, 6, 7, and/or 8 can be changed from a Q to an E.

As used herein, “sequence identity” between two polypeptide sequences indicates the percentage of amino acids that are identical between the sequences. “Sequence similarity” indicates the percentage of amino acids that either are identical or that represent conservative amino acid substitutions. Preferred polypeptide sequences of the invention have a sequence identity in the CDR regions of at least 60%, more preferably, at least 70% or 80%, still more preferably at least 90% and most preferably at least 95%. Preferred antibodies also have a sequence similarity in the CDR regions of at least 80%, more preferably 90% and most preferably 95%. Preferred polypeptide sequences of the invention have a sequence identity in the variable regions of at least 60%, more preferably, at least 70% or 80%, still more preferably at least 90% and most preferably at least 95%. Preferred antibodies also have a sequence similarity in the variable regions of at least 80%, more preferably 90% and most preferably 95%.

DNA Molecules of the Invention

The present invention also relates to uses of DNA molecules that encode an antibody for use in the invention. These sequences include, but are not limited to, those DNA molecules set forth in FIGS. 1a and 2 a.

DNA molecules of the invention are not limited to the sequences disclosed herein, but also include variants thereof. DNA variants within the invention may be described by reference to their physical properties in hybridization. The skilled worker will recognize that DNA can be used to identify its complement and, since DNA is double stranded, its equivalent or homolog, using nucleic acid hybridization techniques. It also will be recognized that hybridization can occur with less than 100% complementarity. However, given appropriate choice of conditions, hybridization techniques can be used to differentiate among DNA sequences based on their structural relatedness to a particular probe. For guidance regarding such conditions see, Sambrook et al., 1989 (Sambrook, J., Fritsch, E. F. and Maniatis, T. (1989) Molecular Cloning: A laboratory manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, USA) and Ausubel et al., 1995 (Ausubel, F. M., Brent, R., Kingston, R. E., Moore, D. D., Sedman, J. G., Smith, J. A., & Struhl, K. eds. (1995). Current Protocols in Molecular Biology. New York: John Wiley and Sons).

Structural similarity between two polynucleotide sequences can be expressed as a function of “stringency” of the conditions under which the two sequences will hybridize with one another. As used herein, the term “stringency” refers to the extent that the conditions disfavor hybridization. Stringent conditions strongly disfavor hybridization, and only the most structurally related molecules will hybridize to one another under such conditions. Conversely, non-stringent conditions favor hybridization of molecules displaying a lesser degree of structural relatedness. Hybridization stringency, therefore, directly correlates with the structural relationships of two nucleic acid sequences. The following relationships are useful in correlating hybridization and relatedness (where T_(m) is the melting temperature of a nucleic acid duplex):

-   -   a. T_(m)=69.3+0.41(G+C) %     -   b. The T_(m) of a duplex DNA decreases by 1° C. with every         increase of 1% in the number of mismatched base pairs.     -   c. (T_(m))_(μ2)−(T_(m))_(μ1)=18.5 log₁₀ μ2/μ1         -   where μ1 and μ2 are the ionic strengths of two solutions.

Hybridization stringency is a function of many factors, including overall DNA concentration, ionic strength, temperature, probe size and the presence of agents which disrupt hydrogen bonding. Factors promoting hybridization include high DNA concentrations, high ionic strengths, low temperatures, longer probe size and the absence of agents that disrupt hydrogen bonding. Hybridization typically is performed in two phases: the “binding” phase and the “washing” phase.

First, in the binding phase, the probe is bound to the target under conditions favoring hybridization. Stringency is usually controlled at this stage by altering the temperature. For high stringency, the temperature is usually between 65° C. and 70° C., unless short (<20 nt) oligonucleotide probes are used. A representative hybridization solution comprises 6×SSC, 0.5% SDS, 5×Denhardt's solution and 100 μg of nonspecific carrier DNA. See Ausubel et al., section 2.9, supplement 27 (1994). Of course, many different, yet functionally equivalent, buffer conditions are known. Where the degree of relatedness is lower, a lower temperature may be chosen. Low stringency binding temperatures are between about 25° C. and 40° C. Medium stringency is between at least about 40° C. to less than about 65° C. High stringency is at least about 65° C.

Second, the excess probe is removed by washing. It is at this phase that more stringent conditions usually are applied. Hence, it is this “washing” stage that is most important in determining relatedness via hybridization. Washing solutions typically contain lower salt concentrations. One exemplary medium stringency solution contains 2×SSC and 0.1% SDS. A high stringency wash solution contains the equivalent (in ionic strength) of less than about 0.2×SSC, with a preferred stringent solution containing about 0.1×SSC. The temperatures associated with various stringencies are the same as discussed above for “binding.” The washing solution also typically is replaced a number of times during washing. For example, typical high stringency washing conditions comprise washing twice for 30 minutes at 55° C. and three times for 15 minutes at 60° C.

Accordingly, the present invention includes the use of nucleic acid molecules that hybridize to the molecules of set forth in FIGS. 1a and 2a under high stringency binding and washing conditions, where such nucleic molecules encode an antibody or functional fragment thereof for uses as described herein. Preferred molecules (from an mRNA perspective) are those that have at least 75% or 80% (preferably at least 85%, more preferably at least 90% and most preferably at least 95%) homology or sequence identity with one of the DNA molecules described herein.

Functionally Equivalent Variants

Yet another class of DNA variants the use of which is within the scope of the invention may be described with reference to the product they encode (see the peptides listed in FIGS. 1b and 2b ). These functionally equivalent genes are characterized by the fact that they encode the same peptide sequences found in FIGS. 1b and 2b due to the degeneracy of the genetic code.

It is recognized that variants of DNA molecules provided herein can be constructed in several different ways. For example, they may be constructed as completely synthetic DNAs. Methods of efficiently synthesizing oligonucleotides in the range of 20 to about 150 nucleotides are widely available. See Ausubel et al., section 2.11, Supplement 21 (1993). Overlapping oligonucleotides may be synthesized and assembled in a fashion first reported by Khorana et al., J. Mol. Biol. 72:209-217 (1971); see also Ausubel et al., supra, Section 8.2. Synthetic DNAs preferably are designed with convenient restriction sites engineered at the 5′ and 3′ ends of the gene to facilitate cloning into an appropriate vector.

As indicated, a method of generating variants is to start with one of the DNAs disclosed herein and then to conduct site-directed mutagenesis. See Ausubel et al., supra, chapter 8, Supplement 37 (1997). In a typical method, a target DNA is cloned into a single-stranded DNA bacteriophage vehicle. Single-stranded DNA is isolated and hybridized with an oligonucleotide containing the desired nucleotide alteration(s). The complementary strand is synthesized and the double stranded phage is introduced into a host. Some of the resulting progeny will contain the desired mutant, which can be confirmed using DNA sequencing. In addition, various methods are available that increase the probability that the progeny phage will be the desired mutant. These methods are well known to those in the field and kits are commercially available for generating such mutants.

Recombinant DNA Constructs and Expression

The present invention further provides for the use of recombinant DNA constructs comprising one or more of the nucleotide sequences of the present invention. The recombinant constructs are used in connection with a vector, such as a plasmid or viral vector, into which a DNA molecule encoding an antibody for use in the invention is inserted.

The encoded gene may be produced by techniques described in Sambrook et al., 1989, and Ausubel et al., 1989. Alternatively, the DNA sequences may be chemically synthesized using, for example, synthesizers. See, for example, the techniques described in OLIGONUCLEOTIDE SYNTHESIS (1984, Gait, ed., IRL Press, Oxford), which is incorporated by reference herein in its entirety. Recombinant constructs of the invention are comprised with expression vectors that are capable of expressing the RNA and/or protein products of the encoded DNA(s). The vector may further comprise regulatory sequences, including a promoter operably linked to the open reading frame (ORF). The vector may further comprise a selectable marker sequence. Specific initiation and bacterial secretory signals also may be required for efficient translation of inserted target gene coding sequences.

The present invention further provides for uses of host cells containing at least one of the DNAs disclosed herein. The host cell can be virtually any cell for which expression vectors are available. It may be, for example, a higher eukaryotic host cell, such as a mammalian cell, a lower eukaryotic host cell, such as a yeast cell, but preferably is a prokaryotic cell, such as a bacterial cell. Introduction of the recombinant construct into the host cell can be effected by calcium phosphate transfection, DEAE, dextran mediated transfection, electroporation or phage infection.

Bacterial Expression

Useful expression vectors for bacterial use are constructed by inserting a structural DNA sequence encoding a desired protein together with suitable translation initiation and termination signals in operable reading phase with a functional promoter. The vector will comprise one or more phenotypic selectable markers and an origin of replication to ensure maintenance of the vector and, if desirable, to provide amplification within the host. Suitable prokaryotic hosts for transformation include E. coli, Bacillus subtilis, Salmonella typhimurium and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus.

Bacterial vectors may be, for example, bacteriophage-, plasmid- or phagemid-based. These vectors can contain a selectable marker and bacterial origin of replication derived from commercially available plasmids typically containing elements of the well known cloning vector pBR322 (ATCC 37017). Following transformation of a suitable host strain and growth of the host strain to an appropriate cell density, the selected promoter is de-repressed/induced by appropriate means (e.g., temperature shift or chemical induction) and cells are cultured for an additional period. Cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification.

In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the protein being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of antibodies or to screen peptide libraries, for example, vectors which direct the expression of high levels of fusion protein products that are readily purified may be desirable.

Therapeutic Methods

Therapeutic methods involve administering to a subject in need of treatment a therapeutically effective amount of an antibody contemplated by the invention. A “therapeutically effective” amount hereby is defined as the amount of an antibody that is of sufficient quantity to deplete CD38-positive cells in a treated area of a subject-either as a single dose or according to a multiple dose regimen, alone or in combination with other agents, which leads to the alleviation of an adverse condition, yet which amount is toxicologically tolerable. The subject may be a human or non-human animal (e.g., rabbit, rat, mouse, monkey or other lower-order primate).

An antibody for use in the invention might be co-administered with known medicaments, and in some instances the antibody might itself be modified. For example, an antibody could be conjugated to an immunotoxin or radioisotope to potentially further increase efficacy.

Disorders and conditions particularly suitable for treatment with an antibody are multiple myeloma (MM) and other haematological diseases, such as chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), acute myelogenous leukemia (AML), and acute lymphocytic leukemia (ALL). An antibody also might be used to treat inflammatory disease such as rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE).

To treat any of the foregoing disorders, pharmaceutical compositions for use in accordance with the present invention may be formulated in a conventional manner using one or more physiologically acceptable carriers or excipients. An antibody for use in the invention can be administered by any suitable means, which can vary, depending on the type of disorder being treated. Possible administration routes include parenteral (e.g., intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous), intrapulmonary and intranasal, and, if desired for local immunosuppressive treatment, intralesional administration. In addition, an antibody for use in the invention might be administered by pulse infusion, with, e.g., declining doses of the antibody. Preferably, the dosing is given by injections, most preferably intravenous or subcutaneous injections, depending in part on whether the administration is brief or chronic. The amount to be administered will depend on a variety of factors such as the clinical symptoms, weight of the individual, whether other drugs are administered. The skilled artisan will recognize that the route of administration will vary depending on the disorder or condition to be treated.

Determining a therapeutically effective amount of the novel polypeptide, according to this invention, largely will depend on particular patient characteristics, route of administration, and the nature of the disorder being treated. General guidance can be found, for example, in the publications of the International Conference on Harmonisation and in REMINGTON'S PHARMACEUTICAL SCIENCES, chapters 27 and 28, pp. 484-528 (18th ed., Alfonso R. Gennaro, Ed., Easton, Pa.: Mack Pub. Co., 1990). More specifically, determining a therapeutically effective amount will depend on such factors as toxicity and efficacy of the medicament. Toxicity may be determined using methods well known in the art and found in the foregoing references. Efficacy may be determined utilizing the same guidance in conjunction with the methods described below in the Examples.

Diagnostic Methods

CD38 is highly expressed on hematological cells in certain malignancies; thus, an anti-CD38 antibody for use in the invention may be employed in order to image or visualize a site of possible accumulation of malignant cells in a patient. In this regard, an antibody can be detectably labeled, through the use of radioisotopes, affinity labels (such as biotin, avidin, etc.) fluorescent labels, paramagnetic atoms, etc. Procedures for accomplishing such labeling are well known to the art. Clinical application of antibodies in diagnostic imaging are reviewed by Grossman, H. B., Urol. Clin. North Amer. 13:465-474 (1986)), Unger, E. C. et al., Invest. Radiol. 20:693-700 (1985)), and Khaw, B. A. et al., Science 209:295-297 (1980)). Preferred antibodies or antigen-binding regions of the invention for use as a diagnostic compound comprise a variable heavy chain sequence selected from the group consisting of SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 and 106 and/or a variable light chain sequence selected from the group consisting of SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 and 110.

The detection of foci of such detectably labeled antibodies might be indicative of a site of tumor development, for example. In one embodiment, this examination is done by removing samples of tissue or blood and incubating such samples in the presence of the detectably labeled antibodies. In a preferred embodiment, this technique is done in a non-invasive manner through the use of magnetic imaging, fluorography, etc. Such a diagnostic test may be employed in monitoring the success of treatment of diseases, where presence or absence of CD38-positive cells is a relevant indicator. The invention also contemplates the use of an anti-CD38 antibody, as described herein for diagnostics in an ex vivo setting.

Therapeutic and Diagnostic Compositions

The antibodies for use in the present invention can be formulated according to known methods to prepare pharmaceutically useful compositions, wherein an antibody for use in the invention (including any functional fragment thereof) is combined in a mixture with a pharmaceutically acceptable carrier vehicle. Suitable vehicles and their formulation are described, for example, in REMINGTON'S PHARMACEUTICAL SCIENCES (18th ed., Alfonso R. Gennaro, Ed., Easton, Pa.: Mack Pub. Co., 1990). In order to form a pharmaceutically acceptable composition suitable for effective administration, such compositions will contain an effective amount of one or more of the antibodies for use in the present invention, together with a suitable amount of carrier vehicle. Preferred antibodies or antigen-binding regions of the invention for use as a diagnostic compound comprise a variable heavy chain sequence selected from the group consisting of SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 and 106 and/or a variable light chain sequence selected from the group consisting of SEQ ID NO: 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 109 and 110.

Preparations may be suitably formulated to give controlled-release of the active compound. Controlled-release preparations may be achieved through the use of polymers to complex or absorb anti-CD38 antibody. The controlled delivery may be exercised by selecting appropriate macromolecules (for example polyesters, polyamino acids, polyvinyl, pyrrolidone, ethylenevinyl-acetate, methylcellulose, carboxymethylcellulose, or protamine, sulfate) and the concentration of macromolecules as well as the methods of incorporation in order to control release. Another possible method to control the duration of action by controlled release preparations is to incorporate anti-CD38 antibody into particles of a polymeric material such as polyesters, polyamino acids, hydrogels, poly(lactic acid) or ethylene vinylacetate copolymers. Alternatively, instead of incorporating these agents into polymeric particles, it is possible to entrap these materials in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatine-microcapsules and poly(methylmethacylate) microcapsules, respectively, or in colloidal drug delivery systems, for example, liposomes, albumin microspheres, microemulsions, nanoparticles, and nanocapsules or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences (1980).

The compounds may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampules, or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

The compositions may, if desired, be presented in a pack or dispenser device, which may contain one or more unit dosage forms containing the active ingredient. The pack may for example comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration.

The invention further is understood by reference to the following working examples, which are intended to illustrate and, hence, not limit the invention.

EXAMPLES

Cell-Lines

The following cell-lines were obtained from the European Collection of Cell Cultures (ECACC), the German Collection of Microorganisms (DSMZ) or the American Type Culture collection (ATCC): hybridoma cell line producing the CD38 mouse IgG1 monoclonal antibody OKT10 (ECACC, #87021903), Jurkat cells (DSMZ, ACC282), LP-1 (DSMZ, ACC41), RPM18226 (ATCC, CCL-155), HEK293 (ATCC, CRL-1573), CHO-K1 (ATCC, CRL-61), Raji (ATCC, CCL-86), and OPM2 (DSMZ, ACC50).

Cells and Culture-Conditions

All cells were cultured under standardized conditions at 37° C. and 5% CO₂ in a humidified incubator. The cell-lines LP-1, RPMI8226, Jurkat and Raji were cultured in RPMI1640 (Pan biotech GmbH, #P04-16500) supplemented with 10% FCS (PAN biotech GmbH, #P30-3302), 50 U/ml penicillin, 50 μg/ml streptomycin (Gibco, #15140-122) and 2 mM glutamine (Gibco, #25030-024) and, in case of Jurkat- and Raji-cells, additionally 10 mM Hepes (Pan biotech GmbH, #P05-01100) and 1 mM sodium pyruvate (Pan biotech GmbH, #P04-43100) had to be added.

CHO-K1 and HEK293 were grown in DMEM (Gibco, #10938-025) supplemented with 2 mM glutamine and 10% FCS. Stable CD38 CHO-K1 transfectants were maintained in the presence of G418 (PAA GmbH, P11-012) whereas for HEK293 the addition of 1 mM sodium-pyruvate was essential. After transient transfection of HEK293 the 10% FCS was replaced by Ultra low IgG FCS (Invitrogen, #16250-078). The cell-line OKT10 was cultured in IDMEM (Gibco, #31980-022), supplemented with 2 mM glutamine and 20% FCS.

Preparation of Single Cell Suspensions from Peripheral Blood

All blood samples were taken after informed consent. Peripheral blood mononuclear cells (PBMC) were isolated by Histopaque®-1077 (Sigma) according to the manufacturer's instructions from healthy donors. Red blood cells were depleted from these cell suspensions by incubation in ACK Lysis Buffer (0.15 M NH4Cl, 10 mM KHCO₃, 0.1 M EDTA) for 5 min at RT or a commercial derivative (Bioscience, #00-4333). Cells were washed twice with PBS and then further processed for flow cytometry or ADCC (see below).

Flow Cytometry (“FACS”)

All stainings were performed in round bottom 96-well culture plates (Nalge Nunc) with 2×10⁵ cells per well. Cells were incubated with Fab or IgG antibodies at the indicated concentrations in 50 μl FACS buffer (PBS, 3% FCS, 0.02% NaN3) for 40 min at 4° C. Cells were washed twice and then incubated with R-Phycoerythrin (PE) conjugated goat-anti-human or goat-anti-mouse IgG (H+L) F(ab′)2 (Jackson Immuno Research), diluted 1:200 in FACS buffer, for 30 min at 4° C. Cells were again washed, resuspended in 0.3 ml FACS buffer and then analyzed by flow cytometry in a FACSCalibur (Becton Dickinson, San Diego, Calif.).

For FACS based Scatchard analyses RPMI8226 cells were stained with at 12 different dilutions (1:2^(n)) starting at 12.5 μg/ml (IgG) final concentration. At least two independent measurements were used for each concentration and K_(D) values extrapolated from median fluorescence intensities according to Chamow et al. (1994).

Surface Plasmon Resonance

The kinetic constants k_(on) and k_(off) were determined with serial dilutions of the respective Fab binding to covalently immobilized CD38-Fc fusion protein using the BIAcore 3000 instrument (Biacore, Uppsala, Sweden). For covalent antigen immobilization standard EDC-NHS amine coupling chemistry was used. For direct coupling of CD38 Fc-fusion protein CM5 senor chips (Biacore) were coated with ˜600-700 RU in 10 mM acetate buffer, pH 4.5. For the reference flow cell a respective amount of HSA (human serum albumin) was used. Kinetic measurements were done in PBS (136 mM NaCl, 2.7 mM KCl, 10 mM Na₂HPO4, 1.76 mM KH₂PO₄ pH 7.4) at a flow rate of 20 μl/min using Fab concentration range from 1.5-500 nM. Injection time for each concentration was 1 min, followed by 2 min dissociation phase. For regeneration 5 μl 10 mM HCl was used. All sensograms were fitted locally using BIA evaluation software 3.1 (Biacore).

Example 1: Antibody Generation from HuCAL Libraries

For the generation of therapeutic antibodies against CD38, selections with the MorphoSys HuCAL GOLD® phage display library were carried out. HuCAL GOLD® is a Fab library based on the HuCAL® concept (Knappik et al., 2000; Krebs et al., 2001), in which all six CDRs are diversified, and which employs the CysDisplay™ technology for linking Fab fragments to the phage surface (Löhning, 2001).

A. Phagemid Rescue, Phage Amplification and Purification

HuCAL GOLD® phagemid library was amplified in 2×TY medium containing 34 μg/ml chloramphenicol and 1% glucose (2×TY-CG). After helper phage infection (VCSM13) at an OD600 of 0.5 (30 min at 37° C. without shaking; 30 min at 37° C. shaking at 250 rpm), cells were spun down (4120 g; 5 min; 4° C.), resuspended in 2×TY/34 μg/ml chloramphenicol/50 μg/ml kanamycin and grown overnight at 22° C. Phages were PEG-precipitated from the supernatant, resuspended in PBS/20% glycerol and stored at −80° C. Phage amplification between two panning rounds was conducted as follows: mid-log phase TG1 cells were infected with eluted phages and plated onto LB-agar supplemented with 1% of glucose and 34 μg/ml of chloramphenicol (LB-CG). After overnight incubation at 30° C., colonies were scraped off, adjusted to an OD600 of 0.5 and helper phage added as described above.

B. Pannings with HuCAL GOLD®

For the selections HuCAL GOLD® antibody-phages were divided into three pools corresponding to different VH master genes (pool 1: VH1/5λκ, pool 2: VH3□ λκ, pool 3: VH2/4/6 λκ). These pools were individually subjected to 3 rounds of whole cell panning on CD38-expressing CHO-K1 cells followed by pH-elution and a post-adsorption step on CD38-negative CHO-K1-cells for depletion of irrelevant antibody-phages. Finally, the remaining antibody phages were used to infect E. coli TG1 cells. After centrifugation the bacterial pellet was resuspended in 2×TY medium, plated on agar plates and incubated overnight at 30° C. The selected clones were then scraped from the plates, phages were rescued and amplified. The second and the third round of selections were performed as the initial one.

The Fab encoding inserts of the selected HuCAL GOLD® phages were subcloned into the expression vector pMORPH® x9_Fab_FS (Rauchenberger et al., 2003) to facilitate rapid expression of soluble Fab. The DNA of the selected clones was digested with XbaI and EcoRI thereby cutting out the Fab encoding insert (ompA-VLCL and phoA-Fd), and cloned into the XbaI/EcoRI cut vector pMORPH® x9_Fab_FS. Fab expressed in this vector carry two C-terminal tags (FLAG™ and Strep-Tag® II) for detection and purification.

Example 2: Biological Assays

Antibody dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity was measured according to a published protocol based on flow-cytometry analysis (Naundorf et al., 2002) as follows:

ADCC:

For ADCC measurements, target cells (T) were adjusted to 2.0E+05 cells/ml and labeled with 100 ng/ml Calcein AM (Molecular Probes, C-3099) in RPMI1640 medium (Pan biotech GmbH) for 2 minutes at room temperature. Residual calcein was removed by 3 washing steps in RPMI1640 medium. In parallel PBMC were prepared as source for (natural killer) effector cells (E), adjusted to 1.0E+07 and mixed with the labeled target cells to yield a final E:T-ratio of 50:1 or less, depending on the assay conditions. Cells were washed once and the cell-mix resuspended in 200 μl RPMI1640 medium containing the respective antibody at different dilutions. The plate was incubated for 4 hrs under standardized conditions at 37° C. and 5% CO₂ in a humidified incubator. Prior to FACS analysis cells were labeled with propidium-iodide (PI) and analyzed by flow-cytometry (Becton-Dickinson). Between 50.000 and 150.000 events were counted for each assay.

The following equation gave rise to the killing activity [in %]:

$\frac{ED^{A}}{{EL^{A}} + {ED^{A}}} \times 100$

with ED^(A)=events dead cells (calcein+PI stained cells), and EL^(A)=events living cells (calcein stained cells)

CDC:

For CDC measurements, 5.0E+04 CD38 CHO-K1 transfectants were added to a microtiter well plate (Nunc) together with a 1:4 dilution of human serum (Sigma, #S-1764) and the respective antibody. All reagents and cells were diluted in RPMI1640 medium (Pan biotech GmbH) supplemented with 10% FCS. The reaction-mix was incubated for 2 hrs under standardized conditions at 37° C. and 5% CO₂ in a humidified incubator. As negative controls served either heat-inactivated complement or CD38-transfectants without antibody. Cells were labeled with PI and subjected to FACS-analysis.

In total 5000 events were counted and the number of dead cells at different antibody concentrations used for the determination of EC50 values. The following equation gave rise to the killing activity [in %]:

$\frac{{ED}^{C}}{{EL^{C}} + {ED^{C}}} \times 100$

with ED^(C)=events dead cells (PI stained cells), and EL^(C)=events living cells (unstained)

Cytotoxicity values from a total of 12 different antibody-dilutions (1:2^(n)) in triplicates were used in ADCC and duplicates in CDC for each antibody in order obtain EC-50 values with a standard analysis software (PRISM®, Graph Pad Software).

Example 3: Generation of Stable CD38-Transfectants and CD38 Fc-Fusion Proteins

In order to generate CD38 protein for panning and screening two different expression systems had to be established. The first strategy included the generation of CD38-Fc-fusion protein, which was purified from supernatants after transient transfection of HEK293 cells. The second strategy involved the generation of a stable CHO-K1-cell line for high CD38 surface expression to be used for selection of antibody-phages via whole cell panning.

As an initial step Jurkat cells (DSMZ ACC282) were used for the generation of cDNA (Invitrogen) followed by amplification of the entire CD38-coding sequence using primers complementary to the first 7 and the last 9 codons of CD38, respectively (primer MTE001 & MTE002rev; Table 4). Sequence analysis of the CD38-insert confirmed the published amino acid sequence by Jackson et al. (1990) except for position 49 which revealed a glutamine instead of a tyrosine as described by Nata et al. (1997). For introduction of restriction endonuclease sites and cloning into different derivatives of expression vector pcDNA3.1 (Stratagene), the purified PCR-product served as a template for the re-amplification of the entire gene (primers MTE006 & MTE007rev, Table 4) or a part (primers MTE004 & MTE009rev, Table 4) of it. In the latter case a fragment encoding for the extracellular domain (aa 45 to 300) was amplified and cloned in frame between a human Vkappa leader sequence and a human Fc-gamma 1 sequence. This vector served as expression vector for the generation of soluble CD38-Fc fusion-protein. Another pcDNA3.1-derivative without leader-sequence was used for insertion of the CD38 full-length gene. In this case a stop codon in front of the Fc-coding region and the missing leader-sequence gave rise to CD38-surface expression. HEK293 cells were transiently transfected with the Fc-fusion protein vector for generation of soluble CD38 Fc-fusion protein and, in case of the full-length derivative, CHO-K1-cells were transfected for the generation of a stable CD38-expressing cell line.

TABLE 4 Primer # Sequence (5′->3′) MTE001 ATG GCC AAC TGC GAG TTC AGC (SEQ ID NO: 123) MTE002rev TCA GAT CTC AGA TGT GCA AGA TGA ATC (SEQ ID NO: 124) MTE004 TT GGT ACC AGG TGG CGC CAG CAG TG (SEQ ID NO: 125) MTE006 TT GGT ACC ATG GCC AAC TGC GAG (SEQ ID NO: 126) MTE007rev CCG ATA TCA* GAT CTC AGA TGT GCA AGA TG (SEQ ID NO: 127) MTE009rev CCG ATA TC  GAT CTC AGA TGT GCA AGA TG (SEQ ID NO: 128) *leading to a stop codon (TGA) in the sense orientation.

Example 4: Cloning, Expression and Purification of HuCAL® IgG1

In order to express full length IgG, variable domain fragments of heavy (VH) and light chains (VL) were subcloned from Fab expression vectors into appropriate pMORPH®_hIg vectors (see FIGS. 7 to 9). Restriction endonuclease pairs BlpI/MfeI (insert-preparation) and BlpI/EcoRI (vector-preparation) were used for subcloning of the VH domain fragment into pMORPH®_hIgG1. Enzyme-pairs EcoRV/HpaI (lambda-insert) and EcoRV/BsiWI (kappa-insert) were used for subcloning of the VL domain fragment into the respective pMORPH®_hIgκ_1 or pMORPH®_h_Igλ_1 vectors. Resulting IgG constructs were expressed in HEK293 cells (ATCC CRL-1573) by transient transfection using standard calcium phosphate—DNA coprecipitation technique.

IgGs were purified from cell culture supernatants by affinity chromatography via Protein A Sepharose column. Further down stream processing included a buffer exchange by gel filtration and sterile filtration of purified IgG. Quality control revealed a purity of >90% by reducing SDS-PAGE and >90% monomeric IgG as determined by analytical size exclusion chromatography. The endotoxin content of the material was determined by a kinetic LAL based assay (Cambrex European Endotoxin Testing Service, Belgium).

Example 5: Generation and Production of Chimeric OKT10 (chOKT10; SEQ ID NOS: 72 and 73)

For the construction of chOKT10 the mouse VH and VL regions were amplified by PCR using cDNA prepared from the murine OKT10 hybridoma cell line (ECACC #87021903). A set of primers was used as published (Dattamajumdar et al., 1996; Zhou et al., 1994). PCR products were used for Topo-cloning (Invitrogen; pCRII-vector) and single colonies subjected to sequence analysis (M13 reverse primer) which revealed two different kappa light chain sequences and one heavy chain sequence. According to sequence alignments (EMBL-nucleotide sequence database) and literature (Krebber et al, 1997) one of the kappa-sequence belongs to the intrinsic repertoire of the tumor cell fusion partner X63Ag8.653 and hence does not belong to OKT10 antibody. Therefore, only the new kappa sequence and the single VH-fragment was used for further cloning. Both fragments were reamplified for the addition of restriction endonuclease sites followed by cloning into the respective pMORPH® IgG1-expression vectors. The sequences for the heavy chain (SEQ ID NO: 72) and light chain (SEQ ID NO: 73) are given in FIG. 6. HEK293 cells were transfected transiently and the supernatant analyzed in FACS for the chimeric OKT10 antibody binding to the CD38 over-expressing Raji cell line (ATCC).

Example 6: Cross Reactivity Analysis by FACS (MOR 03087 and MOR 03088) 1. Materials and Methods:

FIGS. 11 and 12 show FACS analyses of lymphocytes and erythrocytes: EDTA-treated blood samples were obtained from healthy humans (after obtaining informed consent) and from non human primates (Rhesus, Cynomolgus and Marmoset) and were subjected to density gradient centrifugation using the Histopaque cell separation system according to the instructions of the supplier (Sigma). For FACS-analysis, cells from the interphase (PBMC-fraction) and pellet (Erythrocyte-fraction) were incubated with anti-CD38 HuCAL® antibodies in different formats

An overview of cross reactivity profiles of different anti CD38 antibodies is shown in FIG. 13.

2. Summary and Conclusion:

The results show that among all CD38 antibodies only MOR03087 and MOR03088 showed cross-reactivity to marmoset PBMCs. Surprisingly, CD38-expression on marmoset erythrocytes is almost not detectable as compared to the strong expression on cynomolgus and rhesus erythrocytes. Thus, the CD38 expression on marmoset erythrocytes and PBMCs is more reflecting the human situation, where CD38 expression is low on erythrocytes and moderate to high on PBMCs. Marmoset is therefore considered to be suited as a model to study toxicity of molecules binding to CD38.

Based on the above study, it was decided to further optimize the binders MOR 03087 and MOR 03088, as described elsewhere in the specification, see e.g. paragraph relating to “Antibodies for use in the invention”. A person skilled in the art would expect that also the derivative antibodies of the parentals would show a comparable cross reactivity profile.

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1. A method for generating variants of an anti-CD38 antibody comprising a VH of SEQ ID NO:21 and a VL of SEQ ID NO: 51, said method comprising the steps of: i) diversifying one or more amino acid residues within one or more CDR regions or one or more framework regions of the anti-CD38 antibody comprising the VH of SEQ ID NO:21 and the VL of SEQ ID NO: 51; ii) generating a recombinant antibody library comprising antibodies with the one or more diversified amino acid residues; and iii) screening antibodies of the recombinant antibody library against a CD38 antigen.
 2. The method of claim 1, wherein diversification of the one or more amino acid residues is in CDR-3 of the VL, CDR-3 of the VH, CDR-1 of the VL and/or CDR-2 of the VH.
 3. The method of claim 1, wherein diversification of the one or more amino acid residues is in CDR2 of the VH.
 4. The method of claim 1, wherein step i) of diversifying is done by synthesizing a collection of DNA molecules using trinucleotide mutagenesis (TRIM) technology.
 5. The method of claim 1 wherein the generated recombinant library of step ii) is a phage display library.
 6. The method of claim 5 wherein screening in step iii) is performed in a stable CHO-K1-cell line for high CD38 surface expression for selection of antibody-phages via whole cell panning.
 7. A variant of an anti-CD38 antibody comprising a VH of SEQ ID NO:21 and a VL of SEQ ID NO: 51 generated in accordance with claim
 1. 8. The variant of claim 7 which has at least 90% identity in the VH or VL to the anti-CD38 antibody comprising the VH of SEQ ID NO: 21 and the VL of SEQ ID NO:
 51. 